[Python-Dev] package imports, sys.path and os.chdir()
tismer at stackless.com
Thu Apr 26 23:30:40 CEST 2012
I have a small problem/observation with imports.
I have several packages to import, which works all fine, as long
as the packages are imported from directories found on the installed
site-packages, via .pth etc.
The only problem is the automatically prepended empty string in sys.path.
Depending from where I start my application, the values stored
in package.__file__ and package.__path__ are absolute or relative
So, if my pwd is the directory that contains my top-level modules,
even though sys.path contains correct absolute entries for that, in this
case the '' entry wins.
<- cwd is here
>>> import moda
Some code happens to chdir away, and later some code does
>>> from moda import modb
Since the __path__ entry is now a relative path, this second import fails.
Although it is no recommended practice to leave a changed chdir(), I
don't see why this is so. When a module is imported, would it not be
better to always make __file__ and __path__ absolute?
I see the module path, hidden by the '' entry not as a feature but
an undesired side-effect.
No big deal and easy to work around, I just would like to understand why.
cheers -- chris
Christian Tismer :^)<mailto:tismer at stackless.com>
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